1. Field of the Invention
The present invention relates to a semiconductor. acceleration sensor which is mounted on transportation equipment, such as an automobile and airplane, and is used for measuring acceleration and collision thereof, and a manufacturing method thereof.
2. Description of the Related Art
A conventional semiconductor acceleration sensor, comprises a weight section that is an hemispheric-shaped solder attached to a function section supported by flexible sections created on a silicon substrate, and measures acceleration by detecting the change of piezo-resistors created in the flexible sections by aluminum wires (e.g. Japanese Patent Kokai No. H5-264575 (page 2, paragraphs 0006, 0007, and page 3, paragraphs 0017-0020, FIG. 1, FIG. 8)).
In order to fetch signals from the semiconductor acceleration sensor to the outside, normally it is necessary to create electrodes connected to the acceleration measurement elements, and wire them with a terminals connected to the outside using bonding wires. In the above mentioned prior art, it is necessary to create an electrode on a silicon substrate in order to detect the change of the piezo-resistor by aluminum wire, and fetch the signals to the outside, but the shape of the weight section is hemispheric, and the maximum area section thereof is bonded with the function section, so securing an area for creating the electrodes increases the size of the semiconductor acceleration sensor, which is a problem.